1. Field of the Invention
The present invention relates to display systems. In particular, the invention relates to adjusting the size and position of an image on a display device.
2. Background Information
Display devices are often used to transmit information to a user. Display devices typically receive a video signal and convert the video signal into an image for a user to view. The video signal may be received from a variety of sources such as a microprocessor in a computer system, a video storage media such as a video cassette recorder or a television transmission. Examples of devices which are used as display devices or monitors include cathode ray tubes (CRT) devices, liquid crystal display (LCD) devices, and plasma devices.
One common display device is a cathode ray tube (CRT). FIG. 1 illustrates a typical cross-section of a CRT 100. In CRT 100, an electron gun 104 shoots an electron beam 108 through a set of magnets 112 to a fluorescent screen 116. When electrons within the electron beam 108 strike the fluorescent screen 116, the energy of the electrons excites a phosphorous coating causing the fluorescent screen 116 to emit light 120 photons.
The set of magnets 112 direct where the electron beam 108 strikes the fluorescent screen 116. Typically, the set of magnets 112 includes a top magnet 124 and a bottom magnet 128 as well as a first side magnet 132 and a second side magnet 136. Top magnet 124 and bottom magnet 128 move electron beam 108 from the top 130 of the fluorescent surface 116 to the bottom 131 of the fluorescent surface while side magnets 132, 136 move electron beam 108 in a horizontal direction 138 across fluorescent screen 116. Each sweep of the electron beam 108 in a horizontal direction 138 forms a scan line 140 on fluorescent screen 116. Once a scan line 140 has been formed, the vertical magnets including top magnet 124 and bottom magnet 128 apply slightly different magnetic fields to move the electron beam to a new starting position 141 and allow side magnets 132, 136 to again sweep the electron beam across the surface of the fluorescent screen 116 to form an adjacent or subsequent scan line 142. By rapidly moving the electron beam across the screen, a series of scan lines forms an image for display on fluorescent screen 116.
Electronics 144 control the electro magnetic fields created by the set of magnets 112. Electronics 144 also control the firing of electron gun 104. The video electronics 144 typically does this by processing video signals arriving from a processor such as a microcomputer 148. However, current electronics typically do not automatically process the video signal to precisely center an image and properly adjust the size of an image for a particular monitor. Current systems allow manual centering and sizing of an image using physical controls on the screen. Such manual control is awkward and inefficient.
Thus, a method of processing of automatically centering an image and properly setting the resolution of the screen is needed.